Fix quick create on mobile

Summary: Fixes T4903. At some point maybe-soonish we should maybe go make `"device" => true` the default, and put `"device" => "hella-busted"` on the remaining bad pages.

Test Plan: L@@K @ W/ iOS Simulator

Reviewers: chad

Reviewed By: chad

Subscribers: epriestley, k

Maniphest Tasks: T4903

Differential Revision: https://secure.phabricator.com/D8863

src/applications/home/controller/PhabricatorHomeQuickCreateController.php

@@ -29,6 +29,7 @@ final class PhabricatorHomeQuickCreateController
       ),
       array(
         'title' => pht('Quick Create'),
+        'device' => true,
       ));
   }
 

src/applications/people/remarkup/PhabricatorRemarkupRuleMention.php

@@ -18,7 +18,10 @@ final class PhabricatorRemarkupRuleMention
   // username, so we'll incorrectly pick it up, but there's little to be done
   // about that. We forbid terminal periods so that we can correctly capture
   // "@joe" instead of "@joe." in "Hey, @joe.".
-  const REGEX = '/(?<!\w)@([a-zA-Z0-9._-]*[a-zA-Z0-9_-])/';
+  //
+  // We disallow "@@joe" because it creates a false positive in the common
+  // construction "l@@k", made popular by eBay.
+  const REGEX = '/(?<!\w|@)@([a-zA-Z0-9._-]*[a-zA-Z0-9_-])/';
 
   public function apply($text) {
     return preg_replace_callback(